RF to DC passive rectifiers can benefit from the superior performance at low voltage of tunnel transistors. They have shown higher power conversion efficiency (PCE) at low input power than Si FinFETs counterparts. In this paper, we analyze the limitations of typical TFET rectifier topologies associated with the forward biasing of their intrinsic diode and show that this can occur at relatively weak input signals depending on the specific characteristic of the used tunnel device. We propose a simple modification in the implementation of the rectifiers to overcome this problem. The impact of our proposal is evaluated on the widely used gate cross-coupled topology. The proposed designs exhibit similar peak PCE and sensitivity but significantly improve PCE for larger input signal amplitude and larger input power